The instant invention relates to translators for translating representations of the behavior of a particular system into another representation. Specifically, the translator of the invention is useful for translating the behavioral modeling properties of a system into an analog hardware description language (AHDL), which may then be used in a simulation of the behavior of the system. Put another way, the translator is capable of extracting behaviors from symbols representing real-world components, and mapping the extracted behavior into a synthesizer, regardless of the normal entry requirements of the synthesizer.
A number of translators are known which will provide a type of synthesis, translating a description of a system in one form to another form. Such translators are used with analog circuit synthesis, filter synthesis, control system synthesis and digital system synthesis. These types of operations all occur in domains which are restricted to either a netlist, wherein the representations which are created are nothing more than "blocks" hooked together, wherein all of the behavior of each block is predefined elsewhere, such as a SPICE library system; or, an operation wherein the synthesis is derived from a control system and a mathematical description of the behavior is generated, in control system format, which is not a true physical representation of the behavior of a system. In such instances, no physical conservation laws are obeyed, no through-and-across variables; are usable, and/or the system is merely digital, wherein everything is event-driven, wherein there may be legitimate high-level behavior which includes unidirectional signal flow, but which, again, does not obey physical conservation laws. Such synthesis may get to low level circuitry, such as a transistor type implementation, but again, only in a predefined block implementation format.
A true synthesis, as used herein, occurs where a transformation is performed from a representation of requirements to a representation of the associated implementation. Such a synthesis is generally not a circuit level description, although it is conceivable that eventually, the representation may be expressed as a circuit level description which is derived from a specification of the behavior. The invention described herein represents an initial development in CAE software to synthesize a representation from a specification for a physical system.
The behavior of a physical system may be described in terms of how that system will respond to a stimulus with respect to time or frequency. A system which is described in this way is an abstraction of the physical implementation of such a system. Several formulations for these abstractions have been developed in the past, and large bodies of mathematical theory have been developed from them. The formulations for describing systems exhibiting classical physical behaviors include: a system of ordinary nonlinear algebraic differential equations, the Laplace transform expressed as the product of rational polynomials in S, and a frequency response curve expressed as a list of frequency, magnitude and phase triplicates. In sampled data systems, behavior is usually described as a Z-domain transform expressed as the product of rational polynomials in Z or poles and zeros in Z.
System simulators, such as the System Performance Simulator described in U.S. Pat. No. 5,092,780, issued Mar. 3, 1992, describe an analog hardware descriptive language. Using a hardware description language (HDL) requires that the user learn rules and details for generating even the simplest model which is to be simulated. Such models may either be macro-models or may be primitive models. A hardware description language is useful because the behavior may be defined exactly and with great accuracy.
The invention described herein reduces the drawbacks of using a hardware description language because the user is allowed to define the model in terms of the appropriate behavior which is being defined, and is not required to learn the intricacies and details of the hardware description language.